registerReceiver问题

Question

代码未进入registerReceiver功能。你能帮帮我吗（或推荐我可以通过的代码示例）？我正试图找到可用的蓝牙设备。

package com.example.mahe.toddler;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.bluetooth.*;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;

import android.content.Intent;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class Main_Page extends AppCompatActivity {

public BluetoothAdapter btAdapter;
private BluetoothSocket btSocket = null;
private OutputStream outStream = null;
private ArrayList<String> mDeviceList = new ArrayList<String>();


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main__page);

    final ListView listView = (ListView) findViewById(R.id.listView);

    btAdapter=BluetoothAdapter.getDefaultAdapter();
    findViewById(R.id.off).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v)
        {
            if(btAdapter==null)
            {
                Toast.makeText(Main_Page.this, "Bluetooth not enabled phone.", Toast.LENGTH_SHORT).show();
            }
            else
            {
                if (btAdapter.isEnabled())
                {
                    btAdapter.disable();
                }
            }
        }
    });
    final BroadcastReceiver mReceiver = new BroadcastReceiver()
    {
        public void onReceive(Context context, Intent intent)
        {
            String action = intent.getAction();
            Toast.makeText(getBaseContext(), action,Toast.LENGTH_LONG).show();
            if (BluetoothDevice.ACTION_FOUND.equals(action))
            {
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                mDeviceList.add(device.getName() + "\n" + device.getAddress());
                Log.i("BT", device.getName() + "\n" + device.getAddress());
                listView.setAdapter(new ArrayAdapter<String>(context,android.R.layout.simple_list_item_activated_1, mDeviceList));
            }
            else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action))
            {
                Log.v(" ","discovery Finished ");
            }
        }
    };
    findViewById(R.id.on).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v)
        {
            if(btAdapter==null)
            {
                Toast.makeText(Main_Page.this, "Bluetooth not enabled phone.", Toast.LENGTH_SHORT).show();
            }
            else
            {
                if (btAdapter.isEnabled())
                {
                    //do nothing
                    btAdapter.startDiscovery();

                }
                else
                {
                    //Prompt user to turn on Bluetooth
                    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                    startActivityForResult(enableBtIntent, 1);

                    btAdapter.startDiscovery();
                    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
                    registerReceiver(mReceiver, filter);



                }
            }
        }
    });


}

}